/Engine/Source/Editor/BlueprintGraph/Classes/EdGraphSchema_K2.h
Sets the pin defaults, but not autogenerated defaults, at pin construction time. This is like TrySetDefaultValue but does not do validation or callbacks
virtual void SetPinDefaultValueAtConstruction ( [UEdGraphPin](API\Runtime\Engine\EdGraph\UEdGraphPin) * Pin, const [FString](API\Runtime\Core\Containers\FString) & DefaultValueString ) const